This project attempts to define the physiology of the Trp64Arg Beta-3- Adrenergic receptor variant in the development of Non-Insulin Dependent Diabetes Mellitus (NIDDM) and obesity. The protocol calls for the recruitment of 75 individuals with and without the variant allele for comparison studies of resting metabolic rate, 24-hour energy expenditure, body composition, and glucose tolerance and insulin resistance. To date, we have recruited over 600 individuals for genotyping and identified 3 homozygotes and 50 heterozygotes. We have completed 10 inpatient prptocols, and are planning approximately 3 studies per month for the next two years. Preliminary data analysis awaits more subjects completing the inpatient protocol.